In known claw-pole generators, the energy for the excitation is taken from the electrical system of the respective motor vehicle. This takes place using a generator controller that has a switched semiconductor as a switching element. The generator controller sets the excitation voltage between 0 V and the electrical system voltage. This is shown in FIG. 1, which depicts a diagram illustrating the positioning of generator controller R between electrical system BN and excitation winding WE of the generator.
FIG. 2 shows a known generator circuit having a generator controller R, an excitation winding WE, a rectifier system G and three stator windings WS. The stator windings form a star connection, and are offset by 120° from one another with respect to the rotor (not shown). The beginnings of the windings, which are connected to the rectifier system, are designated with the letters U, V, W. When the rotor is turned, an alternating voltage is produced in each of these stator windings. The three alternating voltages produced are offset from one another by 120°.
From German Published Patent Application No. 196 34 096, a voltage supply system is known that has an increased output power, produced when an increased power requirement is signaled by an external control signal. The known system has a three-phase generator whose windings supply the voltage for a vehicle electrical system via rectifiers. In addition, the generator contains an exciter winding through which the excitation voltage, which can be influenced by a voltage controller, flows. The exciter winding can be operated with a voltage that is higher than the supply voltage during times that can be predetermined. This increased voltage is produced through the activation of additional windings having rectifiers in the generator, or by a direct-current converter allocated to the generator. In this way, the controlling of the generator takes place through the voltage controller, which has controlled transistors, in such a way that the output voltage of the generator remains at the level of the electrical system.